(a) Field of the Invention
The present invention relates to a liquid crystal display and, more particularly, to a liquid crystal display which has a wide viewing angle.
(b) Description of the Related Art
Generally, liquid crystal displays have a structure where a liquid crystal is sandwiched between two substrates, and the electric field applied to the liquid crystal changes its arrangement to control light transmission.
Among them, the vertically aligned twisted nematic (VATN) liquid crystal displays have a pair of internal transparent substrates with transparent electrodes, a liquid crystal sandwiched between the substrates, and two polarizing plates externally attached to the substrates one by one. The liquid crystal molecules are initially aligned perpendicular to the substrates and, under the application of an electric field, they are spirally twisted with a predetermined pitch while being oriented to be parallel to the substrates.
When the polarizing plates are normal to each other in the polarizing direction, light is completely blocked when there is no application of an electric field. That is, in the so-called normally black mode, brightness is very low at an off state and hence the contrast ratio is high compared to the usual TN liquid crystal display. However, under the application of voltage (particularly gray scale voltage), a significant difference is present in retardation of light depending upon the viewing directions as in the usual TN liquid crystal display, so that the viewing angle becomes too narrow.
In order to solve such a problem, it has been proposed that the electrodes be patterned to generate fringe fields, and that the fringe fields generate several micro-regions with different orientation directions of the liquid crystal molecules. For instance, U.S. Pat. No. 5,309,264 issued to Lien discloses a technique of forming X-shaped opening portions at the common electrode. U.S. Pat. No. 5,434,690 issued to Histake et al. discloses a technique of forming opening portions at the electrodes of the top and bottom substrates in an alternate manner.
However, the above techniques require a separate mask to pattern the common electrode. Furthermore, since the color filter pigments may influence the liquid crystal, a protective layer must be formed on the color filters. It also generates serious textures at the periphery of the patterned electrodes.